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Import Elevations (AERMAP) |
  
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Import Elevations (AERMAP) |
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BREEZE provides a robust method for importing digital terrain elevation files. This importation process is initialized from the Tools menu.
Note: Terrain elevations that are imported and assigned to model objects are for the model objects current positions. If a model object is moved, or if model objects are added after terrain has been imported, terrain files will need to be re-imported.
Note: To use NTF files and XYZ files for elevation importation, please refer to the next section, Terrain File Formats.
IMPORTANT NOTE: AERMAP is the preprocessor developed US EPA to import model object elevations into AERMOD. AERMAP only supports UTM coordinate system using the following 6 datum, North American Datum of 1927(NAD27), World Geodetic System of 1972(WGS72), World Geodetic System of 1984(WGS84), North American Datum of 1983(NAD83), Old Hawaii Datum, Puerto Rico/ Virgin Island Datum. In cases that any other coordinate systems are used, coordinate system for model objects has to be the same as the coordinate system for the terrain files in order to import elevations with AERMAP.
Starting the Import Elevations Tool
From the Tools menu, select the Import Elevations (AERMAP) menu item. The AERMAP wizard will start.
Import options
You can control what model objects will be processed by BREEZE AERMAP the the use of Import options.
Select the model objects that you want to receive terrain elevations for from the terrain elevation file(s) or DEMs.
Normally, you would want to select all objects listed. It is common to import elevations for receptors and any sources not located onsite (i.e., outside of a boundary receptor). Take care when importing elevations for sources and buildings where a facility grade is not represented in the digital DEM data set. if you add or move a model object (e.g., building, point source) after you have already imported terrain, you may wish to re-import the terrain just for that model object type.
AERMAP Executable
Select the Fortran executable to use when running AERMAP. The BREEZE version is enhanced to allow processing of DEM files for locations outside of the United States and allows for a greater number of receptors to be processed.
Processing options
Process options let the user specify the UTM zone the model objects are located in. This is necessary for the model object’s coordinates to be re-projected onto a zone representative of at least one of the DEMS.
Model Object datum: the datum that your model object (e.g., sources, buildings, and receptors) coordinates are entered as.
UTM zone: the UTM zone the model objects are located in.
Hemisphere: the Hemisphere the model objects are located in.
Visualization options
BREEZE AERMOD can create height maps based on the imported DEM files. Visualization options allow the user to add these height maps to the Map and 3D display windows.
Add terrain surface to 3D view: the height map image will be added to the 3D view.
ADD shaded relief to Map view: the height map image will be added to the Map view.
Resolution: Select the resolution of the height map image. Higher resolution shows more detail, but requires more memory.
Terrain Files
Digital elevation models (DEMs) must be specified. These files contain the terrain elevations for numerous terrain nodes.
Click the Add button to add one or more DEM files. You can import more than one terrain elevation file into the model scenario by clicking the Add button as many the times as needed. Another option is to select multiple files by pressing the CTRL key and selecting individual files or by pressing the SHIFT key and selecting a range of files.
The Datum column will be populated with the appropriate data as read from each terrain file.
Note: BREEZE will allow you to import terrain files that have different units and datum.
DEM boundary and Hill height boundary
DEM boundaries
The image above displays model objects and DEM boundaries. Blue boxes indicate the boundaries of the DEM files. You may have to zoom out using the zoom tool buttons or view extents button in the form to view the complete extent of the DEM boundaries. If no DEM boundary is visible surrounding your modeling objects, it is likely that the DEM files you have selected are inappropriate for your modeling domain. Only model objects within a DEM boundary will have elevations assigned to them.
Hill height boundary
To reduce processing time, AERMAP requires the user to specify the region within the DEM boundaries to compute the receptor hill scale heights. See the AERMAP modeling guidance for more information on how receptor hill scale heights are computed. AERMOD uses this defined region to display the terrain relief in the 3D view. To do this, zoom in to the point where you can see all model objects and the DEM boundaries. With your mouse, click and hold the left mouse button in the lower left hand corner of the modeling domain, and drag the mouse to the upper right hand corner. Purple lines will be displayed showing you the area that will be processed by AERMAP.
Release the mouse after you have reached the upper right hand corner of the region you would like processed. Be sure you have included all your receptors and other modeling objects within the shaded region that is created as you drag your mouse. Terrain elevations will not be imported for model objects outside the hill height boundary and AERMAP will experience a fatal error if the boundary does not encompass all receptors.
Note: The area defined by the user-defined border is the area that will be available for display in the 3D view as a shaded relief image.
After the hill height boundary is defined by the user, the coordinates of its Southwest corner and Northeast corner will be given in the following group box.
Use worst case boundary: Sets the DEM domain based on 10% slope method, which means that within the DEM domain, all terrain elevations exceeding a 10% slope are captured in the hill height boundary.
Undo: Deletes the hill height boundary set by worst case boundary method, allows the user to set the boundary manually.
Run AERMAP
A dialog box will display and ask the user to run AERMAP. After clicking the Yes button, a console window will show and display any messages generated from the run. Close the console window after AERMAP run is finished, the following report window appears.
Reports
The user can click any of the radio buttons to display the files one at a time in the Report panel.
Page url: http://www.breeze-software.com/prod/aermod-isc/help/index.html?import_elevations_aermap.htm